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Dealing with MoFi Ultradeck motor vibration

Discussion in 'Audio Hardware' started by Romany, Apr 16, 2021.

  1. Romany

    Romany Member Thread Starter

    Location:
    New York
    Just wanted to post a promising (maybe) hack for Ultradeck and Studiodeck owners whose deck, like mine, displays an audible motor noise (if yours doesn't, consider yourself lucky - I owned both turntables, each exhibiting the same motor vibration issue).

    Anyway, if you got a noisy MoFi turntable and listen carefully, most likely you will also hear the same quiet motor noise through headphones when the needle skates over dead wax, between the tracks, etc. Once the needle lifts, the noise is gone. So the needle must be picking vibration through the platter somehow. I don't particularly mind hearing the motor noise on dead wax, but I often wondered if the sound in general is affected by the vibration. And now I am fairly convinced that it does.

    To soak the vibration out of the platter, I recently purchased some sorbothane disks on EBay, and placed them under the plinth around the platter spindle area (the discs were about 2 inches in diameter and when stacked, just short of an inch in height). I adjusted the legs so the deck doesn't rest on sorbothane but only touches it. Once everything was in place, I noticed that a) the motor noise while standing next to the table was just as audible, b) the same noise I heard through headphones during quiet passages or on dead wax is practically gone, and finally c) the sound overall became less crunchy and more dampened. The blacks now are much darker.

    I'm still thinking about contacting MoFi while the deck is under warranty to have them look into the motor noise issue. But until then, I might have my deck surf on sorbothane ;)

    Hope this is useful to someone... Of course, YMMV
     
    stax o' wax and rcsrich like this.
  2. patient_ot

    patient_ot Senior Member

    Location:
    USA
    Pretty damn pitiful that a $2K turntable needs a McGuyver workaround to get rid of audible motor noise.

    Something is off here. I wouldn't tolerate it.
     
  3. Romany

    Romany Member Thread Starter

    Location:
    New York
    When last time I contacted MoFi about my StudioDeck noise, their rep had wrote back saying that their decks use high-torque motors that might get noisy. Considering that these motors are rigidly mounted into the plinth, the problem gets only compounded. I really like the way their decks sound though, and so far this was my only gripe. I may still press the issue with them.
     
    Nathan Z and patient_ot like this.
  4. WithinYourReach

    WithinYourReach Resident Millennial

    Location:
    Austin, TX
    Agree with @patient_ot above. You purchased a pretty expensive turntable that shouldn't be having these sort of issues out of the box. I'd press MoFi for a solution and have them fix or replace it.
     
    Last edited: Apr 16, 2021
    jesterthejedi and patient_ot like this.
  5. Davey

    Davey very clever with maracas

    Location:
    SF Bay Area, USA
    I don't have any experience with the MoFi motors, but sometimes AC synchronous motors can be noisy due to distortion on the AC line, which is a big problem for most of us nowadays due to heavy asymmetrical and capacitive loading on the line. The peak distortion can result in a DC component on the line, and is especially troublesome for toroidal transformers without any air gap in the core, it leads to core saturation and high noise levels.

    One thing you could try is to record some of the noise and check the frequency components. Also try turning off other circuits in the house. Maybe try to borrow some type of clean AC regenerator to power the motor, or try a DC blocker on the turntable power.
     
    stax o' wax, patient_ot and Romany like this.
  6. Romany

    Romany Member Thread Starter

    Location:
    New York
    Currently the deck is running from a cheap power conditioner (I also tried running it straight from the wall outlet) but a friend has IsoTek unit - I might borrow it to see if it makes a difference. I will also try a DC blocker - unrelated to this problem, I purchased PS Audio unit some time ago but that didn't change the sound in my system and I shipped it back.
     
    patient_ot likes this.
  7. patient_ot

    patient_ot Senior Member

    Location:
    USA
    If the motors they use have issues with noise, they need to account for that in the design of the turntable or find a different motor to put on these things. No excuse for it.
     
    jesterthejedi, luckybaer and Romany like this.
  8. WhatDoIKnow

    WhatDoIKnow I never got over it, I got used to it

    Location:
    Italy
    UltraDeck owner here :wave:
    I noticed a rather annoying hum when I first started using the TT but the noise has progressively disappeared as I went from the interconnects that come with the UD to better ones. Whatever is left is definitely negligible, and I can't imagine that it has to do with the motor - but I have been known to be wrong in the past so feel free to criticise my thoughts.
     
    displayname likes this.
  9. Romany

    Romany Member Thread Starter

    Location:
    New York
    Very funny, considering your name ;)

    This is not hum here, but a motor noise - like you stand next to the deck and you hear a noise from the motor, just like you would hear an engine noise standing next to the car (although not nearly as loud). So basically, a crappy motor but perhaps my electrical wiring is at fault? I'm going to look into a DC blocker or a good power conditioner to see if that makes any difference, before I press on.
     
  10. Helom

    Helom Forum member

    Location:
    U.S.
    Can you describe the noise in more detail?

    Is it a knocking? And if so, is that what you’re hearing on the dead wax through your cans? Or is it more of a whirl or rumble that you’re hearing through the headphones?
     
    WhatDoIKnow likes this.
  11. Phil Thien

    Phil Thien Forum Resident

    Location:
    Milwaukee, WI
    Ifi makes an inline DC blocker. Amazon sells them for about $80. If you got a male to female IEC cord you could make it into a cord wart.

    Try it, return if it doesn't fix the issue.
     
    patient_ot likes this.
  12. Romany

    Romany Member Thread Starter

    Location:
    New York
    It's a quiet motor noise, mechanical in nature, audible even when the entire system except the table is shut off. And yes, I hear this same noise through the cans during quiet passages. It's very subtle but still quite discernable esp. through the headphones hooked up directly to Ultraphono preamp head out (it has a fairly high noise floor)

    Exactly what I did yesterday: ordered both iFi DC blocker (previously I was unfamiliar with what it does) and iFi conditioner plug. Because both Studiophono I previously had, and Ultraphono I have now exhibit exactly the same type of motor noise, perhaps the electrical interference at my house is at fault.
     
    patient_ot likes this.
  13. macster

    macster Forum Resident

    Location:
    San Diego, Ca. USA
    My VPI Classic one suffered from this and it drove me crazy. I loved the deck but hated the noise, sadly I had to rid up of it. I tried everything except an outboard motor which probably would have done the trick. Good luck and like has been mentioned previously see if you can return the deck if your fixes don't work.

    M~
     
    patient_ot likes this.
  14. Bob_in_OKC

    Bob_in_OKC Forum Resident

    Location:
    Dallas
    Out of curiosity, I'll be very interested to hear how the DC blocker works out. It seems like a possible cause of Pro-Ject's infamous motor noise issue.
     
  15. Davey

    Davey very clever with maracas

    Location:
    SF Bay Area, USA
    Yea, most companies have given up on AC sync motors now and gone with DC servo motors, same as back in the vintage era, more expensive but generally get rid of the noise problem, my 40 year old Micro BL-91 with 12V DC servo motor and heavy platter is dead quiet. A few have stayed with AC sync, VPI, Rega, Pro-Ject, MoFi, and some others, they do give you long term speed stability without a user adjustment, or some type of feedback system, but too prone to noise these days.
     
    Last edited: Apr 17, 2021
    patient_ot, Romany and macster like this.
  16. Helom

    Helom Forum member

    Location:
    U.S.
    Most likely the mechanical noise is from the motor’s rotor bearing design. If the motor is exposed from the bottom of the plinth, you might be able to push upward slightly on the rotor shaft and note whether the noise goes away.
     
  17. Phil Thien

    Phil Thien Forum Resident

    Location:
    Milwaukee, WI
    Well, let us know whether it helps, it could help quite a few users of decks w/ AC motors.
     
    rcsrich, Romany and patient_ot like this.
  18. luckybaer

    luckybaer Thinks The Devil actually beat Johnny

    Location:
    Missouri
    “Our turntables use high-quality, high-torque motors, peasant! You’ll get hum and you’ll like it!”

    Love,
    MoFi Customer Support
     
    Ctiger2, VinylSoul, rcsrich and 3 others like this.
  19. Romany

    Romany Member Thread Starter

    Location:
    New York
    Alas, neither iFi DC blocker nor power conditioner plug helped with the motor noise. Glad I run this experiment still - it's an additional proof that the motor itself is at fault and may need to get looked at by MoFi.

    Otherwise, I think the power conditioner made the phono preamp output a little quieter - it's a handy gizmo to have but will ship DC blocker back.
     
    Last edited: Apr 21, 2021
    patient_ot likes this.
  20. Phil Thien

    Phil Thien Forum Resident

    Location:
    Milwaukee, WI
    Any idea what MoFi have done to isolate the motor from the plinth?
     
    patient_ot likes this.
  21. Romany

    Romany Member Thread Starter

    Location:
    New York
    As far as I know, nothing. It's rigidly mounted into the plinth with four screws. The platter spindle/bearing assembly is solidly mounted into the plinth with three screws. So vibration, direct from the motor or resonance, is passed onto the platter and that's what I partially cured by using sorbothane disks placed under the spindle area (see the OP). Not sure how the arm is mounted and if it's isolated from the plinth though I doubt it since rigidity between the platter and the arm would be desired. That said, when it's raised, the arm is completely silent (through headphones, max volume).

    It's still an awesome deck. The vibration is a big issue for me but my experience with it otherwise, has been very positive.
     
  22. patient_ot

    patient_ot Senior Member

    Location:
    USA
    Get MOFI to send you a new motor or new deck. If that doesn't solve it, time to move on and get your money back. Motor noise like that can also get worse over time, so it's not something you should tolerate.
     
  23. rednedtugent

    rednedtugent Forum Resident

    Location:
    Funk, Ohio
    hmmm, so much for Stereophile's instant classic review. :shake:
     
    jesterthejedi and luckybaer like this.
  24. patient_ot

    patient_ot Senior Member

    Location:
    USA
    It may well be that their sample didn't have a noisy motor. Since MOFI uses off the shelf industrial motors, if they get a bad batch, that's what you get when you buy your table. They could demand better motors, send the noisy ones back, etc. but most of the rubber band turntable companies don't do this. In most cases, you get whatever they get and that's it.
     
    jesterthejedi, luckybaer and Romany like this.
  25. Davey

    Davey very clever with maracas

    Location:
    SF Bay Area, USA
    Supposedly it does have some isolation (below in italics is what they say), but apparently not very effective, I know that VPI also uses the 300 RPM Hurst motors and have had similar issues in more recent times. I still think some of it is probably caused by AC line distortion, but not much a user can do about it except use a low distortion regenerator-type power supply, and they can get expensive, and aren't always effective. The MoFi isolation may just be referring to the three aluminum plates on top bonded to the MDF plinth body below, with the motor mounted to a separate plate from the platter and tonearm, not sure. Anyway, I know some of them do have quiet motors, pretty frustrating situation, hope you get it resolved to your satisfaction, if you can hear the motor when stylus is on the record it's not really acceptable.

    Motor vibrations are kept away from the platter and stylus by using advanced dampening materials that decouple the motor from the rest of the turntable.
     
    Romany and patient_ot like this.

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